It is common to combine the magnetic heads of a tape player/recorder into an integrated head to follow the longitudinal tracks of a magnetic tape. The integrated head is affixed to a carrier plate which is spring mounted on a drive chassis between a head drum and a capstan shaft.
It is well known in the art that the quality of playback and recording using an integrated magnetic head is dependent upon the proper orientation of the integrated head with respect to the tape. Therefore, the carrier plates which support the integrated heads must include facilities for adjusting the angle of inclination, the azimuth and the height of the head with respect to the tape.
The integrated heads of conventional VHS video recorders contain record/playback heads (R/P heads) and an erase head for audio signals in the longitudinal tracks of the magnetic tape. Integrated heads also contain an additional magnetic head (CTL head) to record and playback a control signal (CTL). The control signal serves as a reference signal for the band servo system to phase regulate the tape drive in the playback mode. The control signal is obtained during the recording mode from frame synchronization pulses of a video input signal.
In order to ensure synchronization between the video signals which are recorded in the helical tracks of the magnetic tape and the associated audio signals which are recorded in the longitudinal tracks, and also when playing cassettes recorded on other machines, it is necessary to adjust the X-distance of the integrated head along with the tilt, azimuth and height adjustments. The X-distance is the tape length between the stationary integrated head and a given reference point at the end of the tape looped around the cylinder. The actual X-distance is dependent on the particular recorder system standard; for example, 79.244 mm for a VHS recorder between the CTL head and the reference point at the end of the tape loop. The adjustments can be made electronically using a microprocessor which may be switched into a corresponding operating mode. Such an electronic adjustment process using a microprocessor is described in more detail in DE 35 28 452. Magnetic tape recorders in which the X-distance of the combined head can be adjusted electronically, require, as a result, no additional adjustment capability for the head carrier plate.
It is also known that adjustable-tension compression springs can be used to spring mount the head carrier plates. The springs press the carrier plate against adjustable-height stops whereby the adjustable-height stops create a pre-stress in the respective compression springs. The prestress provides energy needed for the aforementioned adjustments of the integrated head. There are further magnetic tape recorders known in which the capstan shaft is located outside the cassette loaded into the magnetic tape recorder.